Biology Fundamentals

Introduction to Biology

• An atom is matter's smallest unit, comprised of protons, neutrons, and electrons.
• Biology is the scientific study of life and living organisms.
• The biosphere is the global ecological system integrating all living beings and their interactions with Earth's environments.
• A cell is the basic structural and functional unit of all living organisms.
• A community is a group of interacting populations of different species in a shared habitat.
• A control is an experiment component that remains constant, providing a baseline for comparison.
• Deductive reasoning is a logical approach where specific predictions are made from general principles.
• Descriptive science is scientific research focused on observation and description rather than experimentation.
• An ecosystem is a biological community interacting with its physical environment.
• Eukaryotes are organisms whose cells contain a nucleus and membrane-bound organelles.
• Evolution is the process of genetic change in populations over generations, leading to diversity.
• Falsifiable refers to a hypothesis that can be empirically disproven through experimentation.
• Homeostasis is the maintenance of stable internal conditions in an organism.
• A hypothesis is a testable explanation for a scientific question.
• Hypothesis-based science is research driven by hypothesis formulation and testing.
• Inductive reasoning is the derivation of general principles from specific observations.
• Macromolecules include large structures like proteins, nucleic acids, carbohydrates, and lipids.
• A molecule consists of two or more atoms chemically bonded.
• An organ is a structure composed of tissues performing a specific function.
• An organ system is a group of organs working together for a major physiological function.
• An organelle is a specialized structure within eukaryotic cells, like mitochondria.
• An organism is an individual living entity.
• A peer-reviewed article is a scholarly publication evaluated by experts in the field.
• Population refers to members of the same species inhabiting a specific area.
• A prokaryote is a unicellular organism lacking a nucleus, such as Bacteria.
• Science involves use of a systematic method to study the natural world through evidence.
• A scientific law is a description of a consistent natural phenomenon, like gravity.
• The scientific method is an inquiry process involving observation, hypothesis, experimentation, and conclusion.
• A scientific theory is a well-supported explanation of natural phenomena, like evolution.
• Tissue is a group of similar cells performing a specialized function.
• A variable is a factor manipulated or measured in an experiment.

Cell Structure and Function

• There are two cell types: prokaryotic (no nucleus, simple) and eukaryotic (nucleus, complex).
• Both cell types have DNA, cytoplasm, and membranes, while eukaryotes also have organelles.
• Animal and plant cells share nuclei, mitochondria, ER, and Golgi apparatus.
• Plant cells uniquely have chloroplasts, cell walls, and large vacuoles, while animal cells have lysosomes and centrioles.

Organelles

• Nucleus stores DNA.
• Rough ER facilitates protein synthesis via ribosomes
• Smooth ER is responsible for lipid synthesis and detoxification.
• Ribosomes are responsible for protein assembly.
• Golgi apparatus modifies and packages molecules.
• Lysosomes function as digestive enzymes.
• Peroxisomes break down toxins.
• Vesicles and vacuoles are used for storage and transport.
• Centrioles aid cell division in animal cells.
• Chloroplasts conduct photosynthesis in plant cells.
• Mitochondria produce ATP.
• The Plasma Membrane regulates transport.
• The Cell Wall provides structural support to plant cells.
• Plasmodesmata and Gap Junctions facilitate cell communication.
• Cytoplasm is the gel-like matrix within cells.
• Nucleoid is the DNA region in prokaryotic cells.
• The cytoskeleton maintains cell shape, allows movement, & transports materials; microtubules guide organelle movement and chromosome separation
• Cilia and flagella both aid motility; cilia are short/hair-like, while flagella are long/tail-like.
• Light microscopes use visible light, while electron microscopes use electrons for higher resolution.
• The endosymbiosis theory posits that mitochondria and chloroplasts came from engulfed prokaryotes.
• The fluid mosaic model describes the plasma membrane as a phospholipid bilayer with embedded proteins, cholesterol, and carbohydrates.

Transport Terms

• Selective permeability controls substance passage.
• Passive transport requires no energy (e.g., diffusion).
• Osmosis is the movement of water across membranes.
• Tonicity is the effect of a solution on cell volume.
• Diffusion rate is affected by gradient, temperature, molecule size, and medium density.
• Active transport requires ATP to move substances against gradients.
• Electrochemical gradient combines chemical and charge differences.

Tonicity Effects

• Isotonicity means no net water movement because there is equal solute concentration to the reference solution.
• Hypotonicity causes a cell to swell (animal cell lyses; plant cell becomes turgid) because there's lower solute concentration than the reference solution
• Hypertonicity causes a cell to shrink (animal cell shrivels; plant cell plasmolysis) because there is a higher solute concentration than the reference solution
• Plants prefer hypotonic environments, while animals require isotonic (osmoregulation) environments.
• Exocytosis expels materials, endocytosis (phagocytosis, pinocytosis, receptor-mediated) imports materials.

How Cells Obtain Energy

• Bioenergetics is the energy flow in cells. Metabolism is the sum of cellular reactions.
• Anabolic reactions build molecules, while catabolic reactions break down molecules.

Thermodynamics

• The 1st Law states energy is conserved.
• The 2nd Law states that entropy (disorder) increases, and heat disperses energy.
• Kinetic energy is energy of motion, Potential energy is stored energy.
• Chemical energy is energy stored in bonds (e.g., glucose).
• Free energy is usable energy.
• Exergonic reactions release energy, while endergonic reactions absorb it.
• Enzymes lower activation energy and the substrate binds to the active site via induced fit.
• Competitive inhibitors block active sites, while noncompetitive inhibitors change enzyme shape.
• Cofactors (ions) and coenzymes (vitamins) assist enzymes.
• Feedback inhibition uses products to regulate enzyme activity, preventing overproduction.
• ATP is made of adenine, ribose, and three phosphates.
• Hydrolysis releases energy (exergonic), while phosphorylation (ADP → ATP) is endergonic.
• Glycolysis breaks glucose into pyruvate, producing 2 ATP, and happens in the cytoplasm (anaerobic).
• Citric Acid Cycle occurs in the mitochondrial matrix, producing ATP, NADH, and FADH2.
• Oxidative Phosphorylation occurs in the inner membrane and uses the electron transport chain (ETC) to make ATP (aerobic).
• Fermentation is anaerobic and produces 2 ATP.
• Lactic acid fermentation occurs in muscle cells, while alcohol fermentation occurs in yeast.
• Non-glucose metabolism involves carbohydrates entering glycolysis, proteins yielding amino acids, and lipids splitting into glycerol/fatty acids.

Photosynthesis

• Autotrophs produce food via photosynthesis (plants), while heterotrophs consume others (animals).
• Photosynthesis equation: 6CO2 + 6H2O + light → C6H12O6 + 6O2; occurs in chloroplasts (thylakoids and stroma).
• Light reactions occur in thylakoids, splitting H2O and producing ATP/NADPH.
• The Calvin cycle occurs in the stroma, fixing CO2 into glucose.
• Wavelength determines energy; shorter (violet) wavelengths have more energy.
• Visible spectrum is 380–750 nm.
• Photosynthesis produces O2 and glucose, which cellular respiration uses, creating CO2 and H2O for plants. Chloroplasts and mitochondria enable energy cycling.
• In Glycolysis: Yes C6H12O6 is used, X 6O2 is used, X 6H20 is used, X 6CO2 is used, 2 ATP is produced (substrate level), 2 NADPH is produced, X FADH is produced, 2 molecules of pyruvate (3C) are produced.
• In Pyruvate Oxidation: X C6H12O6 is used, X 6O2 is used, X 6H20 is used, 2 6CO2 is used, X ATP production, 2 NADH is produced, X FADH is produced and 2 molecules of acetyl-coA (2c) are produced.
• In The Citric Acid Cycle: X C6H12O6 is used, X 6O2 is used, X 6H20 is used, 4 6CO2 is produced, 2 ATP is produced (substrate level synthesis), 6 NADH is produced, 2 FADH is produced,
• In Electron Transport: X C6H12O6 is used, Yes 6O2 is used, Yes 6H20 is used, substrate level ATP production, 30 NADH is used, 4 FADH is used, ETC is used
• Cellular respiration formula: C6H12O6 + 6O2 → 6H2O + 6CO2 + ATP
• Substrate-level ATP synthesis uses enzymes that remove a phosphate from an intermediate molcule and attaches it to ADP to create useable ATP
• Chemiosmosis requires H+ gradient to make ATP
  • Utilizes the enzyme ATP synthase
• O2 (oxygen) is the final electron receptor in the electron transport chain

Test your knowledge of the fundamental concepts in biology. This quiz covers topics such as cell structure, scientific method, ecology, evolution, experimental controls, biological organization, cell types, solutions, cellular transport, and energy.